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| 1 | Freeze–thaw effects on erosion process in loess slope under simulated rainfall显示文摘Seasonal freeze–thaw processes have led to severe soil erosion in the middle and high latitudes.The area affected by freeze–thaw erosion in China exceeds 13%of the national territory.So understanding the effect of freeze–thaw on erosion process is of great significance for soil and water conservation as well as for ecological engineering.In this study,we designed simulated rainfall experiments to investigate soil erosion processes under two soil conditions,unfrozen slope(UFS)and frozen slope(FS),and three rainfall intensities of 0.6,0.9 and 1.2 mm/min.The results showed that the initial runoff time of FS occurred much earlier than that of the UFS.Under the same rainfall intensity,the runoff of FS is 1.17–1.26 times that of UFS;and the sediment yield of FS is 6.48–10.49 times that of UFS.With increasing rainfall time,rills were produced on the slope.After the appearance of the rills,the sediment yield on the FS accounts for 74%–86%of the total sediment yield.Rill erosion was the main reason for the increase in soil erosion rate on FS,and the reduction in water percolation resulting from frozen layers was one of the important factors leading to the advancement of rills on slope.A linear relationship existed between the cumulative runoff and the sediment yield of UFS and FS(R2>0.97,P<0.01).The average mean weight diameter(MWD)on the slope erosion particles was as follows:UFS0.9(73.84μm)>FS0.6(72.30μm)>UFS1.2(72.23μm)>substrate(71.23μm)>FS1.2(71.06μm)>FS0.9(70.72μm).During the early stage of the rainfall,the MWD of the FS was relatively large.However,during the middle to late rainfall,the particle composition gradually approached that of the soil substrate.Under different rainfall intensities,the mean soil erodibility(MK)of the FS was 7.22 times that of the UFS.The ratio of the mean regression coefficient C2(MC2)between FS and UFS was roughly correspondent with MK.Therefore,the parameter C2 can be used to evaluate soil erodibility after the appearance of the rills.This article explored the influence mechanism of freeze–thaw effects on loess soil erosion and provided a theoretical basis for further studies on soil erosion in the loess hilly regions. | SU Yuanyi LI Peng REN Zongping XIAO Lie ZHANG Hui | 2020 | Journal of Arid Land2020,12,6: | 2 |
| 2 | Influence of opening ratios and directions of windows on natural smoke exhaust effect in atrium buildings显示文摘In this paper,the influence of different opening ratios and different opening directions of the windows on the natural smoke exhaust was studied through a series of real fire experiments and simulation analysis.Increasing the open area of the window could effectively improve the overall smoke exhaust effect.When the top windows were open and the opening ratio increased from 19.2%to 24.3%,the optical density was decreased by 12.4%.The average smoke exhaust rate per unit area of the window did not change significantly.Increasing the area of the natural smoke exhaust window could effectively increase the smoke exhaust rate and improve the overall effect of smoke extraction.When the top windows were open,the temperature rise on the top floor was 30.8%-47.5%lower while the visibility was 16.8%-21.9%higher than that when the side windows were open. | Peng Wang Xiankun Wang Keheng Chen Hongyu Wei Qianhang Feng Yuanyi Xie Xuechao He Yanqiu Chen | 2022 | Building Simulation2022,15,4: | 1 |
| 3 | Melatonin inhibits Gram-negative pathogens by targeting citrate synthase显示文摘Bacterial infections caused by Gram-negative pathogens represent a growing burden for public health worldwide.Despite the urgent need for new antibiotics that effectively fight against pathogenic bacteria,very few compounds are currently under development or approved in the clinical setting.Repurposing compounds for other uses offers a productive strategy for the development of new antibiotics.Here we report that the multifaceted melatonin effectively improves survival rates of mice and decreases bacterial loads in the lung during infection.Mechanistically,melatonin specifically inhibits the activity of citrate synthase of Gram-negative pathogens through directly binding to the R300,D363,and H265 sites,particularly for the notorious Pasteurella multocida.These findings highlight that usage of melatonin is a feasible and alternative therapy to tackle the increasing threat of Gram-negative pathogen infections via disrupting metabolic flux of bacteria. | Fang He Yuan Liu Pan Li Xiaoyan Wu Yaoyao Xia Dong Zhang Nengzhang Li Yuanyi Peng Guoqiang Zhu Rüdiger Hardeland Russel JReiter Wenkai Ren | 2022 | Science China(Life Sciences)2022,65,7: | 0 |
| 4 | Microstructure Evolution of Primary γ′ Phase in Ni3Al-Based Superalloy显示文摘In this work,water cooling,air cooling(AC)and furnace cooling(FC)were applied to investigate the effect of cooling rate on microstructure evolution of primaryγ′in a newly designed Ni3Al-based alloy.The results showed that nucleation rate of primaryγ′increased with increasing cooling rate.In addition,higher cooling rate shortened growth period of primaryγ′,which made its morphology close to the initial precipitatedγ′.For AC and FC specimens,due to the lower cooling rate,primaryγ′possessed longer growth period and its morphology was mainly due to the evolution of lattice misfit betweenγand primaryγ′.Meanwhile,growth of primaryγ′depended on lattice misfit distribution between its corner and edge area.Moreover,primaryγ′morphologies of sphere,cube and concave cube with tip corners were illustrated by considering interaction between elemental diffusion and elastic strain energy. | Xin He Jianbo Zhang Yuanyi Peng Jingan Li Jian Ding Chang Liu Xingchuan Xia Xueguang Chen Yongchang Liu | 2020 | Acta Metallurgica Sinica(English Letters)2020,33,12: | 0 |